I am using z3 to extract the unsat core of an unsatisfiable linear constraint set. I find z3 may give a different unsat core for the same problem when setting the "auto-config" option to false. Does there exist other options which may make z3 give a different unsat core for the same problem?
Here is my previous related question: How to get multiple different unsat cores or make the core smaller
There is no specific API for getting different unsatisfiable cores, but you can use the existing API to retrieve some or all minimal cores. The following tutorial
http://rise4fun.com/Z3Py/tutorial/musmss
illustrates in a simplified way how to retrieve multiple cores (or all) and multiple maximal satisfying sets (or all) at the same time.